1. Field of the Invention
The present invention generally relates to a catalyst converter having honeycomb body of which temperature can rise at an early stage and a catalyst carrier which holds a catalyst capable of creating an oxidation-reduction reaction with the toxic elements in the exhaust gas, and of which temperature can rise at an early stage to the activation temperature where catalyst held in the catalyst carrier can perform catalyst functions to purify exhaust gas of automobiles, etc.
2. Description of the Related Art
Conventionally, as means to convert the toxic elements such as CO, and HOx found in the exhaust gas of automobile engines into harmless vapors (such as CO2) or water, a metal catalyst converter that was a catalyst converter comprising a metal catalyst carrier was intervened in the honeycomb placed inside the exhaust gas passage. With these means, the exhaust gas was purified.
Metal catalyst carriers formed by winding or laminating metal foil flat sheets or corrugated sheets are disclosed in the Japanese Utility Model Application Laid-Open No. 4-62316. However, with the metal catalyst carrier disclosed in Japanese Utility Model Application Laid-Open No. 4-62316 a problem existed. When the exhaust gas temperature at the initial engine running state was low, the catalyst properties were not activated, and the exhaust gas was not purified. This was caused because the heat capacity of the metal catalyst carrier itself was extremely large, it took a long time for the held catalyst to rise to the active temperature by just the heat transfer of the exhaust gas heat.
To resolve this problem, Japanese Utility Model Application Laid-Open No. 2-223622 proposed installing a catalyst converter comprising a self-heating type metal catalyst carrier besides the main catalyst converter to activate the catalyst properties by conducting and heating the self-heating metal catalyst carrier. However, a large power exceeding 1 kW is required for this type of catalyst converter, and thus the efficiency is extremely poor.
Furthermore, the metal catalyst carrier for automobiles is installed in the engine exhaust gas passage and is direct subjected to exhaust gases that exceed 900.degree. C. Thus, a repeated function of thermal expansion and contraction is applied. Thus, a metal catalyst carrier provided with slits on the entire metal foil flat sheet and corrugated sheet to absorb the thermal expansion and contraction was disclosed in Japanese Utility Model Application Laid-Open No. 3-71177.
However, with the metal catalyst carrier disclosed in Japanese Utility Model Application Laid-Open No. 3-71177, as fine long slits are formed throughout the flat sheet and corrugated sheet to extend in the direction that crosses with the exhaust gas direction, not only does the rigidity of the metal catalyst carrier itself drop, but also the characteristic frequency drops making it extremely difficult to secure the reliability in regard to the engine vibration. Furthermore, the metal catalyst carrier may break when the strength of the metal drops remarkably at high temperatures exceeding 900.degree. C.
Furthermore, as slits are arranged throughout the metal foil flat sheet and corrugated sheet that configure the metal catalyst carrier, it is extremely difficult to join the flat sheet and corrugated sheet, making complicated manufacturing device, and causing difficulties in inexpensive manufacturing.